Burner control system



March 6, 1945. Q m v I I 2,371,057

BURNER CONTROL SYSTEM Filed Au 5, 1940 lnnentor dmJ new A. attorneg Patented Mar. 6, 1 945 UNITED STATES PATENT OFFICE 2,371,057 BURNER CONTROL SYSTEM Oran T. Mcllvaine, St. Charles, Ill.

Application August 5, 1940, Serial N0. 351,459 a 6 Claims.

This invention relates to an improvement in' burner control systems, and more particularly for use as a safety system for oil or gas burners, to discontinue the operation thereof, if the flame becomes extinguished.

Various attempts have been made heretofore to provide for the automatic control 'of the fuel to an oil or other burner in response to the operation thereof, and to some extent these have proposed the operation of the control system in response to a photo-electric cell or other light sensitive device, but such systems have not been entirely satisfactory for use.

The object of this invention is to improve the operation of the control system for a burner, whereby the operation of the burner will be responsive to the fiame thereof, and yet provision is made for a definite time interval for starting and for automatically shutting off the burner if its flame does not start and continue operation during this time interval, the system being en-.

tirely fool-proof in its operation-and performance.

In carrying out this object, I have provided a pair of electronic discharge tubes connected in parallel and arranged to control a pair of relays, one of the tubes functioning in response to the energizing of a photo-electrictube, and one of the relays controlling the operation of the burner, whilethe other relay has as one of its functions, actuation at a delayed time interval after the operation of the first relay, to prevent V operation of the burnerin the event that the flame thereof becomes extinguished or the burner does not function. This delayed time interval is governed by the heating or cooling intervals of the second tube; which may be varied by the substitution of different tubes, so as to change the starting interval as may be desired.

These and other features will be evident from a full description of the invention as illustrated in the accompanying drawing, which is a diagrammaticview showing an embodiment of this invention in a burner control system.

I have shown the invention applied to a conventional form of oil burner designated'generally by the numeral l, and having a compressor or blower shown at 2, which is adapted to receive operating current from a power line 3 through a branch 3'. Also connected in the power line 3 is a thermostatic control switch 4 and a main power switch 5,'of the usual construction. The power line 3 extends to a control board 6 having fuses 1, and through which the power line ex- 9, the opposite sides of which are connected with a pair. of'anodes in a double rectifier tube III, while the cathode thereof is indirectly heated from a Winding II of the transformer 8.

V A.pair of relays are shown at l3 and I2 which are connected in series with each other and respectively with the cathode of the rectifier tube l0 and with the anodes of a pair of amplifier electronic discharge tubes 14 and I5 which tubes are connected in parallel with each other. The grid of the tube I 4 is connected through a line IS with the cathode of a photo-electric cell 11 that is arranged to receive light from the flame f the burner I when the latter is operating.

The cathodes of the tubes l4 and I5 are indirectly heated, the heaters thereof being connected through circuits l8- and I9 respectively with secondary coils l8 and IQ of the transformer 8. The coil l9 having one side connected with the heater of the tube l5, has its opposite side in a circuit 20 that includes a contact switch I 3a of the relay I3. a

When the main power line switch 5 is closed, as well as the thermostatic switch 4, or other control provided in the power line,':-current will of the tube I5, and the line 2|. The line 22 includes the windings of both relays l2 and I3, and the closing of this circuit upon the energizing of the tube l5, thereby energizes both relays l2 and l3.

The energizing of the relay l2 breaks a circuit at I 2a and closes'a circuit at l2b which latter switch connects a line 23 leading from one side of the power "line 3 with a line 24 that extends to an electro-magnet 25 which controls a power line switch 25 in the line 3' leading to the com'- pressor or other operating part of the burner to actuate the burner, it being ignited either automatically r manually in the usual way. The light from the burner l which would thus fall on the photo-electric tube l1, causes current to flow through said tube between the line I 6', I 6, ex-

tending from the transformer secondary 9, and a line H connected with the cathode of the tube I4, which circuit thereby starts an electronic emission in the tube I4, completing the circuit through the line 22 and the rectifier tube I t0 the transformer secondary 9. This closed circuit will continue to hold the relay I2 energized and to maintain the control circuit 24 closed at the switch I2b for the operation of the oil t irner. This will continue as long as the light from the burner is maintained on the photo-electric cell II. However, if the flame from the burner is interrupted or extinguished, the described. circuit through the photocell I1 and the tube I4 is broken and the relay I2 becomes deenergized, opening the circuit 24 at I2b and disconnecting the power circuit to the burner motor 2, thereby stopping the operation of the burner. The closing of the contact switch I2a upon deenergizing of the relay l2, while the relay I3 remains energized, causes a short circuit around the coil of the, relay I2 through the switch I2a, one side of which is connected through a line I20 with a contact of the switch I3b and which switch has the other contact thereof connected with a line 21 that extends to the line 22 between the coils of the relays I2 and I3. This short circuit prevents the energizing of the relay I2 again until after the relay I3 has been deenergized and the operation repeated.

When the burner was started as described above, if it did not become ignited and. thus produced no flame on the photo-electric cell H, the tube I4 would not function to hold the relays energized. When the relay I3 was energized initially, its actuation opened the contact switch I3a, thus breaking the circuit I9, 20 that supplied current to the heater of the tube I5, allowing the cathode thereof to cool. When it has cooled to a.

' predetermined extent, its emission stops, breaking the circuit through the relay I2. The deenergizing of'the relay I2 after this delayed time interval, opens the control circuit 24 to the burner by opening the contact switch I2b, the relay I2 being deenergized, since the tube I4 was not operated because of the failure of the burner to supply light to the photo-electric cell IT.

The relay I3 has not become deenergized however, because when it was operated initially, it closed a contact switch I30, having a line 28 leading to one side thereof from the secondary coil 9, while the opposite side of the switch I30 is connected with the line 21 leading to the line 22 between the relays I2 and I3. Thus the initial energizing of therelay I3 completeda locking circuit through 21 and 28 and theswitch I3'c, thence through the winding of the relay I3 and the line 22, thereby .maintaining the coil of said relay energized until the main power line circuit 3 is opened. To restart the burner, it is only necessaryto open the main line switch again and then to close it, which repeats the cycle of operation as described above. v

This provides for a fool-proof control of the burner. with a definite starting time interval which functions to discontinue the operation of the burner, or the supply of power thereto auto- 7 matically in the event that its flame is not ignited or becomes extinguished. Different starting time intervals may be obtained, as desired, merely by changing the tube I5 and replacing it with a tube of a different heating time. Thus, a tube requira minute, which will thereby vary the starting time during which the system will function before discontinuing the operation of the burner if no flame has been produced.

The relays I2 and I3 preferably are set at different tensions, the relay I2 having the contact springs thereof of a lighter tension than those of the relay I3 so they will yield before those of the relay I3, whereby the relays will function in the proper order. This is also provided by the connection between the switches I2a and I3b of the relays.

Another feature of this system, as distinguished from a thermo controlled system as frequently employed heretofore, is that regardless of an increased heating of the cathode of the tube I5, it merely delivers an increased emission as a result thereof until the relay I3 is energized to break the heater circuit of said tube I5 at I3a, and thereby discontinuing the operation of this tube. Thus the relay of this tube functions to interrupt its own heater, as described.

I claim:

1. In a burner control system, the combination with a-burner, of an electrical circuit for controlling the operation of the burner, a relay having a contact switch for controlling said circuit, a second. relay having a contact switch adapted to be opened upon energization of said second relay, an electronic discharge device including an anode and a time-delay cathode of appreciable heat capacity, a source of power, a second circuit connecting in series said relays, anode, cathode and source of power, a third circuit controlling the energization of said cathode and including said second relay contact switch, a fourth circuit including said relays and source of power, and means responsive to combustion at the burner for energizing said fourth circuit, thereby normally maintaining said relays energized when-the cathode of said discharge device, after a predetermined .time delay, has cooled to a non-emitting temperature.

2. In a burner control system, the combination with a burner, of an electrical circuit for controlling the operation of the burner, a relay having a contact switch for controlling said circuit, a second relay having a contact switch adapted to be opened upon energization of said second relay, an electronic discharge device including an anode and a time-delayv cathode of appreciable heat capacity, a source of power, a second circuit connecting in series said relays, anode, cathode'and source of power, a third circuit controlling the energization of said cathode and including said second relay contact switch, a fourth circuit including said relays and source of power, and means responsive to combustion at theburner for energizing said fourth circuit, thereby normally maintaining said relays energized when the cathode of said discharge device, after a pre-.

determined time delay, has cooled to a nonemittingv temperature, and a fifth circuit including the second relay and having a contact switch arranged to hold the second relay energized upondeenergizing of the first relay.

3. In a burner control system, the combination of an electrical circuit for controllin the operation of a burner, a relay having a contart ing fifteen seconds for heating or cooling'may be" replaced by one requiring thirty secondsor even switch for controlling saidcircuit, a second relay having a. contact switch responsive to energizetion of said second relay, an electronic discharge device including an anode and a time-delay cathode of an'appreciable heat capacity, a source of power, a second circuit connected in SellUS with said relays, anode, cathode and source of power, a third circuit controlling the energization of said cathode and including said second relay contact switch, a. fourth circuit including said relays and source of power, and mean constructed for operation in response to combustion at the burner for energizing said fourth circuit, thereby normally maintaining said relays energized when the cathode of said discharge device,

after a predetermined time-delay, has cooled to a non-emitting temperature.

4. In a burner control system, the combination 7 of an electrical circuit for controlling the operation of a burner, electrical means for controlling the operation of said circuit, an electronic discharge device including an anode and a timedelay cathode of appreciable heat capacity, a

source of power, a second circuit connected in series with said control means, anode, cathode and source of power, a third circuit for controlling the energization of said cathode and including means for deenerg'zing the cathode, and means responsive to com ustion at the burner for controlling said circuits to normally main-' tain said first-mentioned control means energized when the cathode of said discharge device, after a predetermined time-delay, has cooled to a nonemitting temperature.

5. In a burner control, electrical mean for controlling the operation of a burner circuit, an electronic discharge device including an anode and a time-delay cathode of appreciable heat capacity, means adapted to be connected with a source of power for connecting said electrical controlling means in a circuit with the anode and cathode, means for controlling the energizing of the cathode and including means for deenergizing the cathode, and means responsive to combustion at the burner for controlling the severalaforesaid means normally to maintain the first-mentioned control means energized when the cathode of said discharge device, after a predetermined time delay, has cooled to a non-emitting temperature.

6. In a burner control, the combination of a relay having a contact switch adapted for controlling an electric circuit of a burner, a second relay having a contact switch responsive to energizing'of said second relay, an electronic discharge device including an anode and atimedelay cathode of appreciable heat capacity, means adapted to be connected with a source of electrical power for connecting said anode and cathode in series with said relays, means for controlling the energizing of said, cathode and including said second relay contact switch, and means constructed for operation in response to combustion at the burner for energizing said relays, thereby normally maintaining said relays energized when the cathode of said discharge device, after 'a predetermined time delay, has cooled to a non-emitting temperature.

ORAN T. McILVAINE. 

